1. Biological explanation for OCD
4.1.4 Psychopathology:
The biological approach to explaining OCD: genetic and neural explanations

2. Basic assumptions of biological approach
Remember these?
Everything psychological is at first biological
The approach investigates how biological structures and processes within the body impacts on behaviour.
Much of human behaviour has a physiological cause which may be genetically or environmentally altered.
Genes affect behaviour and influence individual psychological differences between people. Evolutionary psychology considers genetic influences in common behaviours
Psychologists should study the brain, nervous system and other biological systems, e.g. hormones, chemicals acting on the brain

3. Genetics
OCD (obsessive compulsive disorder) has been explained in a number of ways but the biological approach offers particularly useful suggestions as to how it is caused.
It has been proposed that there is a genetic component to OCD which predisposes some individuals to the illness.
The genetic explanation suggests that whether a person develops OCD is at least partly due to their genes. This may explain why patients often have other family members with OCD.

4. Genetics
Bellodi et al (2001) claim that genetic factors play a role in the disorder. Using evidence from twin studies and family studies, they showed that close relatives are more likely to have the disorder than more distant relatives.
Mckeon and Murray- patients with OCD are morel likely to have first degree relatives who suffer from anxiety disorders.
Pauls et al- there is a much higher percentage of OCD sufferers in relatives of patients with OCD than in the control group without OCD.

5. Genetic explanations
Candidate genes are ones which, through research, have been implicated in the development of OCD.
A possible candidate gene is the SERT gene which is involved in regulating serotonin, a neurotransmitter which facilitates message transfer across synapses.
Another possible candidate gene is the COMT gene – this regulates the production of dopamine
Dopamine effects motivation and drive

6. Genetic explanations
It is recognised however that not everyone in a given family gets OCD so there must be additional factors.
The diathesis–stress model suggests that people gain a vulnerability towards OCD through genes but an environmental stressor is also required. This could be a stressful event, for example a bereavement.
OCD is thought to be polygenic – this means that its development is not determined by a single gene but a few (maybe as many as 230 genes) – this means that there is little predictive power from this explanation.

7. Evaluation of genetic explanations
Genetics
There is evidence to suggest there is a genetic component to the disorder. One of the best sources of evidence for the importance of genes is twin studies (Nestadt – 2010)
Family studies could also be used to explain environmental influences
Close relatives of OCD sufferers may have observed and imitated the behaviour (SLT)
It is difficult to untangle the effects of environment and genetic factors

8. Evaluation of genetic explanations
Candidate genes
Candidate genes are ones which, through research, have been implicated in the development of OCD.
There are too many genes involved
Psychologists have not been successful at pinning down all the genes involved
Each genetic variation only increases the risk of OCD by a fraction

9. Evaluation of genetic explanations
Environmental factors
Individuals may gain a vulnerability towards OCD through genes that is then triggered by an environmental stressor.
Cromer (2007) found that over half the OCD patients in their sample had a traumatic event in the past, and that OCD was more severe in those with more than one trauma.
This means that it may more productive to focus on environmental causes as it seems that not all OCD is entirely genetic in origin

10. Neural explanations
The genes associated with OCD are likely to affect the levels of key neurotransmitters as well as structures of the brain
These are neural explanations
Abnormal levels of certain neurotransmitters
Certain brain circuits may be abnormal

11. Neural explanations
Neuroimaging (brain scans) techniques have enabled researchers to study the brain in detail and to identify normal brain patterns - this therefore allows for comparisons with abnormal brain patterns
Researchers have implicated a part of the brain known as the basal ganglia.
This area of the brain is responsible for innate psychomotor functions
Rapport and Wise proposed the hypersensitivity of the basal ganglia gives a rise to the repetitive motor behaviours seen in OCD, for example, repetitive washing/cleaning/checking

12. Neural explanations
Other brain areas believed to be involved in OCD include the orbitofrontal cortex (OFC) and the thalamus
The thalamus is a brain area whose functions include cleaning, checking and other safety behaviours.

13. The orbital frontal cortex
Neural explanations
The OFC is involved in decision making and worry about social and other behaviour. In OCD the OFC and the thalamus are believed to be overactive.
An overactive thalamus would result in an increased motivation to clean or check for safety. If the thalamus was overactive the OFC would also become overactive as a result.
An overactive OFC would result in increased anxiety and increased planning to avoid anxiety.
The orbital frontal cortex

14. Neural explanations

15. Evaluation of neural explanations
The role of neurotransmitters
Allows medication to be developed which helps sufferers.
Drugs are not completely effective
Just because administering SSRIs decreases OCD symptoms does not mean that this was the cause in the first place
There is time delay between taking drugs to target the condition and any improvements being made and yet the chemical imbalance is addressed in hours

16. Evaluation of neural explanations
Areas of the brain
Advances in technology have allowed researchers to investigate specific areas of the brain more accurately, and OCD sufferers do seem to have excessive activity in the orbital frontal cortex
Cleaning and checking behaviours are "hard-wired" in the thalamus
The repetitive acts (compulsions) may be explained by the structural abnormality of the basal ganglia but not necessarily the obsessional thoughts.
There are inconsistencies found in the research as no system has been found that always plays a role in OCD
These neural changes could be as a result of suffering from the disorder, not necessarily the cause of it

17. Can you…? Explain the role of genes in OCD. (4 marks)
Explain two limitations of genetic explanations for OCD. (4 marks)
Outline the neural basis of OCD (4 marks)
Briefly describe one argument in favour of a neural basis to OCD. (2 marks)
Evaluate the biological approach to explaining OCD. (8 marks)

18. Essay
Describe and evaluate the biological approach to explaining OCD (12 marks – AS/16 marks A level)